1. Field of the Invention
The present invention relates to an apparatus for elevating one end portion of a bed such as the head board portion for maintaining one's head elevated slightly above the chest or torso while recumbent, as is medically necessary for a great number of individuals with ailments such as gastro-esophogeal reflux, congestive heart failure, sleep apnea, chronic sinusitis, or edema of the arm. More particularly, the present invention relates to an improved bed lift apparatus that can be selectively positioned by a user under either the head or foot end portion of a bed frame so that after retiring, one may simply push a button to selectively raise the head or foot end portion of a bed. Even more particularly, the present invention relates to an improved electrical bed lift apparatus that uses a single electrical drive motor interfaced with a gear box having two rotary drive shafts for operating a pair of spaced apart screw jacks, each jack having a traveling nut portion that elevates an adjustable beam that supports the head or foot end of the bed frame, the beam including receptacles at a lower elevation that receive two of the casters or feet of the bed.
2. General Background of the Invention
Maintaining one's head elevated slightly above the chest or torso while recumbent is medically advantageous for a great number of individuals with ailments such as gastro-esophageal reflux, congestive heart failure, sleep apnea, chronic sinusitis, and edema of the arm.
Gastro-esophageal reflux is a very common problem affecting persons of all walks of life. Pregnant women are plagued by reflux in the middle and final trimesters of pregnancy. Overweight men and women may have reflux of gastric contents chronically. This causes esophageal strictures and, in come cases, cancer of the lower esophagus.
Since this problem is exacerbated when recumbent, reflux often leads to chest pain in the early morning hours. Treatment may consist of several strategies. First, eating early in the evening several hours before retiring lessens reflux. Second, medications can decrease reflux and decrease the acidity of the refluxed gastric contents. Third, gravity can be used to lessen reflux by elevating the head of one's bed. A mattress wedge, or bricks or blocks have been used but these are not aesthetically pleasing and are frequently awkward or difficult in manipulation.
One of the solutions for elevating one's head slightly above the chest while recumbent is to use an elevating mechanism. Many such bed elevating mechanisms have been patented. Some of these elevating mechanisms are complex mechanisms that are permanently attached to, or a part of, the bed. Other mechanisms are simpler, being placed underneath the feet (legs) or casters of the bed. Still others are adjustable to different elevational positions.
The Lindquist U.S. Pat. No. 2,522,759 discloses an adjustable bed which has a built-in elevating mechanism. The device uses a manual cranking arrangement to selectively raise or lower the head or foot portion of the bed. This apparatus would not be useful as a elevating device for use with any standard or differently sized bed frame since the apparatus is permanently incorporated into the bed frame, providing complicated gearing and internal telescoping portions as part of the overall mechanism. The Swenson U.S. Pat. No. 3,247,528 discloses a bed with a permanently incorporated bed tilting mechanism. The apparatus includes a plurality of pulleys and cables that are used to elevate the person's head, foot, or the middle portion of the bed or a combination thereof.
The Schaefer U.S. Pat. No. 3,073,635 entitled "Shaft Coupling" discloses a hospital bed that includes a head board and foot board with a mattress support that can be elevated. The angle of the bed may be adjusted to suit various medical conditions. In that regard, the head board or foot board can be selectively or jointly elevated. The apparatus is permanently attached to and a part of the bed mechanism. The apparatus uses a motor that can be operated in either direction so that the head of the bed will be appropriately elevated or lowered.
The Burke U.S. Pat. No. 3,310,289 discloses a scissor-like elevator mechanism for an end of a bed. The Burke patent discloses basically a scissors jack that can be placed at the end or intermediate of a conventional bed in order to raise or lower the end portion, or the whole of the bed. The scissors jack lifts the bed frame at a position in between the feet rather than engaging and lifting the feet of the bed. Scissor jacks, if not enclosed, pose a substantial risk of pinch injury.
A portable bed adjusting device for patients and the like is disclosed in U.S. Pat. No. 4,312,088. The device includes bed elevating blocks adapted to be inserted under one end of the bed and longitudinally extending mattress retainers adapted to be inserted between the mattress and the mattress support such as the box spring, to secure the mattress against longitudinal movement when the bed is inclined. The bed elevating blocks include two separate connectable components that are adjustable relative to each other to provide elevation of one selected end of the bed. These blocks are in the form of threadably engaged portions that can be lengthened or shortened in order to attain the desired elevational position. The user must separately adjust each of the blocks before placing them under the appropriate end portions of the bed.
A bed sore prevention device in an bed arrangement for an invalid patient is the subject of U.S. Pat. No. 4,654,903. The '903 patent provides a reversible motor that drives a ball nut through a worm screw so that motion of the ball nut in one direction raises one side of the bed frame and motion in an opposite direction raises the opposite side of the bed frame. As with the Burke invention described above, scissor type apparatus presents a substantial exposure to pinch injuries, including loss of digits.
The Butler U.S. Pat. No. 4,715,073 discloses a tiltable bed frame assembly which permits one to adjust the angular disposition of a mattress between a horizontally disposed position and an inclined position while at the same time permitting one to utilize a conventional mattress and the head board and foot board components of the user's suite. The apparatus incorporates a ramp that is moved with a telescoping pushrod wherein casters travel up the inclined ramp in order to elevate one end of the bed.
The McGinley U.S. Pat. No. 5,224,227 discloses an elevator stand for a bed leg for tilting the bed for use by a person with various conditions. The stand has a base portion for resting on a floor surface, and has an upper receiving portion which has a top surface recess with a bottom bearing surface and an inner sidewall surface telescoping over the bed leg. The elevator is provided with a means for securing the legs of the bed to the elevators. The '227 patent is thus in the form of a static block placed under the legs of a bed.
Another elevator block for raising one end of a bed is seen in U.S. U.S. Pat. No. 5,345,631. The '631 patent discloses an apparatus for raising one end of the bed which comprises placement of elevator blocks under the support legs of the bed. Each of the blocks has top and bottom ends that are non-parallel planar surfaces. The planar surface of the top end is inclined to allow for proper mating of the top end of the elevator block with a bed leg in the bed's raised position. Provision is also made for a removable insert in a cavity of the top end of the elevator block, so that the bed legs can sit either within the cavity for increased stability or upon the top of the insert, depending upon the size of the bed leg. The use of slip-resistant materials on the surfaces contacting either the floor or bed leg also adds stability of the bed in the raised position. Thus, the '631 patent does not enable the bed to be selectively raised or lowered to any desired elevational position between a maximum and a minimum position but rather is a fixed elevation block member simply placed underneath the legs of the bed at the head end portion.
An inclinable bed frame assembly is disclosed in U.S. U.S. Pat. No. 5,566,412. The '412 patent uses multiple bed frame sections that pivot one with respect to the other. A scissor jack arrangement is used to raise an upper frame relative to a lower frame for elevating the entire mattress into a desired elevational position and at an angular elevation with respect to the underlying floor.